Madagascar's eastern rainforest
A 1,500-kilometre green spine of ancient, isolated forest, the wettest and most species-rich corner of the island, and one of the most reduced.
The biome at a glance
A world of its own
The eastern rainforest runs the full length of Madagascar's Indian Ocean escarpment. Warm, wet and geologically stable for a very long time, it has been evolving in isolation since before the dinosaurs disappeared.
The families that dominate it, Apocynaceae, Rubiaceae, Myristicaceae and Clusiaceae, have followed their own paths here for around 88 million years. The result is a plant life, and a plant chemistry, unlike anything in their relatives on the African, Asian or South American mainland. It is one of the reasons this forest holds such scientific interest: much of what grows here has simply never been studied.
Warm, wet and undisturbed for tens of millions of years, the eastern rainforest is where Madagascar's flora reaches its fullest expression.
Characteristic families
| Family | Malagasy genera of note | Known for |
|---|---|---|
| Apocynaceae | Tabernaemontana, Voacanga, Catharanthus | Distinctive alkaloid chemistry; new species still being described |
| Rubiaceae | Ixora, Gaertnera | One of the largest and least-studied families in the forest |
| Clusiaceae | Garcinia, Mammea | Trees of the wet understory and canopy |
| Myristicaceae | Nutmeg relatives | Aromatic, tropical, largely endemic here |
The rose periwinkle
The most famous plant ever found in this forest is Catharanthus roseus, the rose periwinkle. Its compounds, vincristine and vinblastine, became cornerstones of treatment for childhood leukaemia and Hodgkin lymphoma, and have saved many lives around the world.
Madagascar, the country whose forests produced that chemistry, saw very little of the value that followed. That history is one of the reasons the Nagoya Protocol exists, and why IsoGentiX builds fair, traceable, benefit-sharing access in from the start. What was taken once should not be taken the same way again.
A forest under pressure
The eastern rainforest has lost more than four-fifths of its original extent to clearing, logging and charcoal production, and what remains is fragmented and still shrinking. The surviving corridors, around Ranomafana, Andringitra, Masoala and Mananara, are the last strongholds of much of this diversity.
Many of the species most worth understanding are also the most threatened. When a forest fragment is lost, the plants in it, and everything they evolved over millions of years, are lost with it. Documenting this biome now is part of protecting it.